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suppose that professor degroot has a policy of giving as to the top 10% of student scores on his final, regardless of the actual scores. if the distribution of scores on his final exam turns out to be normal with mean 69 and standard deviation 9, how high does your score have to be to earn an a?



Answer :

varshamittal029

Your score must be greater than or equal to 81 in order to receive an A grade.

Here, we are given that professor Degroot has a policy of giving A grade to the top 10% of student scores on his final.

This means in order to earn an A grade, your score should be in the top 10%.

⇒ Z score should be 0.09

we can look at the z tables to find that this value is at z = 1.28

Now, we know z score is calculated as-

z = (X - μ)/ σ

where X = observed value

μ = sample mean

σ = standard deviation

substituting the given values in the formula we get-

1.28 = (X - 69)/ 9

1.28 × 9 = X - 69

11.52 = X - 69

X = 11.52 + 69

X = 80.52

Thus, your score must be greater than or equal to 81 in order to receive an A grade.

Learn more about z tables here-

https://brainly.com/question/25638875

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